This invention related to the preparation of malonic anhydride and substituted malonic anhydrides, and to the preparation of useful derivatives thereof. The invention is particularly directed to novel procedure for the preparation of malonic anhydrides, particularly malonic anhydride and dimethyl malonic anhydride, and to the preparation of unsymmetrical derivatives of malonic acids, particularly the corresponding monoesters and monoamides, from such anhydrides.
Although the dibasic acids, succinic and glutaric acids, form cyclic anhydrides upon dehydration, dehydration of malonic acid does not yield the anhydride, but leads instead to a gas, carbon suboxide, C.sub.3 O.sub.2. Although substituted malonic anhydrides can be obtained under dehydrating conditions, these are polymeric and not monomeric.
Further, unsymmetrical derivatives or monoderivatives of malonic acids, such as the monoesters or monoamides, are difficult compounds to prepare and are expensive, such derivatives having utility in the preparation of drugs.
One object of the present invention is the production of malonic anhydride and substituted malonic anhydrides. Another object is the provision of novel procedure for the preparation of malonic anhydride and substituted malonic anhydrides. A further object of the invention is to provide procedure for readily converting malonic anhydrides and substituted malonic anhydrides to derivatives of such anhydrides, particularly the unsymmetrical derivatives such as the monoesters and monoamides. Yet another object is to provide procedure for preparing such derivatives of malonic anhydrides by first preparing the malonic anhydrides and without isolating such anhydrides, reacting the latter in the same solution with a derivatizing agent such as an alcohol or an amine.